~bzr-pqm/bzr/bzr.dev

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
# Copyright (C) 2004 Aaron Bentley <aaron.bentley@utoronto.ca>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
import os.path
import errno
import patch
import stat
from bzrlib.trace import mutter
from bzrlib.osutils import rename

# XXX: mbp: I'm not totally convinced that we should handle conflicts
# as part of changeset application, rather than only in the merge
# operation.

"""Represent and apply a changeset

Conflicts in applying a changeset are represented as exceptions.
"""

__docformat__ = "restructuredtext"

NULL_ID = "!NULL"

class OldFailedTreeOp(Exception):
    def __init__(self):
        Exception.__init__(self, "bzr-tree-change contains files from a"
                           " previous failed merge operation.")
def invert_dict(dict):
    newdict = {}
    for (key,value) in dict.iteritems():
        newdict[value] = key
    return newdict

       
class ChangeUnixPermissions(object):
    """This is two-way change, suitable for file modification, creation,
    deletion"""
    def __init__(self, old_mode, new_mode):
        self.old_mode = old_mode
        self.new_mode = new_mode

    def apply(self, filename, conflict_handler, reverse=False):
        if not reverse:
            from_mode = self.old_mode
            to_mode = self.new_mode
        else:
            from_mode = self.new_mode
            to_mode = self.old_mode
        try:
            current_mode = os.stat(filename).st_mode &0777
        except OSError, e:
            if e.errno == errno.ENOENT:
                if conflict_handler.missing_for_chmod(filename) == "skip":
                    return
                else:
                    current_mode = from_mode

        if from_mode is not None and current_mode != from_mode:
            if conflict_handler.wrong_old_perms(filename, from_mode, 
                                                current_mode) != "continue":
                return

        if to_mode is not None:
            try:
                os.chmod(filename, to_mode)
            except IOError, e:
                if e.errno == errno.ENOENT:
                    conflict_handler.missing_for_chmod(filename)

    def __eq__(self, other):
        if not isinstance(other, ChangeUnixPermissions):
            return False
        elif self.old_mode != other.old_mode:
            return False
        elif self.new_mode != other.new_mode:
            return False
        else:
            return True

    def __ne__(self, other):
        return not (self == other)


def dir_create(filename, conflict_handler, reverse):
    """Creates the directory, or deletes it if reverse is true.  Intended to be
    used with ReplaceContents.

    :param filename: The name of the directory to create
    :type filename: str
    :param reverse: If true, delete the directory, instead
    :type reverse: bool
    """
    if not reverse:
        try:
            os.mkdir(filename)
        except OSError, e:
            if e.errno != errno.EEXIST:
                raise
            if conflict_handler.dir_exists(filename) == "continue":
                os.mkdir(filename)
        except IOError, e:
            if e.errno == errno.ENOENT:
                if conflict_handler.missing_parent(filename)=="continue":
                    file(filename, "wb").write(self.contents)
    else:
        try:
            os.rmdir(filename)
        except OSError, e:
            if e.errno != errno.ENOTEMPTY:
                raise
            if conflict_handler.rmdir_non_empty(filename) == "skip":
                return
            os.rmdir(filename)


class SymlinkCreate(object):
    """Creates or deletes a symlink (for use with ReplaceContents)"""
    def __init__(self, contents):
        """Constructor.

        :param contents: The filename of the target the symlink should point to
        :type contents: str
        """
        self.target = contents

    def __call__(self, filename, conflict_handler, reverse):
        """Creates or destroys the symlink.

        :param filename: The name of the symlink to create
        :type filename: str
        """
        if reverse:
            assert(os.readlink(filename) == self.target)
            os.unlink(filename)
        else:
            try:
                os.symlink(self.target, filename)
            except OSError, e:
                if e.errno != errno.EEXIST:
                    raise
                if conflict_handler.link_name_exists(filename) == "continue":
                    os.symlink(self.target, filename)

    def __eq__(self, other):
        if not isinstance(other, SymlinkCreate):
            return False
        elif self.target != other.target:
            return False
        else:
            return True

    def __ne__(self, other):
        return not (self == other)

class FileCreate(object):
    """Create or delete a file (for use with ReplaceContents)"""
    def __init__(self, contents):
        """Constructor

        :param contents: The contents of the file to write
        :type contents: str
        """
        self.contents = contents

    def __repr__(self):
        return "FileCreate(%i b)" % len(self.contents)

    def __eq__(self, other):
        if not isinstance(other, FileCreate):
            return False
        elif self.contents != other.contents:
            return False
        else:
            return True

    def __ne__(self, other):
        return not (self == other)

    def __call__(self, filename, conflict_handler, reverse):
        """Create or delete a file

        :param filename: The name of the file to create
        :type filename: str
        :param reverse: Delete the file instead of creating it
        :type reverse: bool
        """
        if not reverse:
            try:
                file(filename, "wb").write(self.contents)
            except IOError, e:
                if e.errno == errno.ENOENT:
                    if conflict_handler.missing_parent(filename)=="continue":
                        file(filename, "wb").write(self.contents)
                else:
                    raise

        else:
            try:
                if (file(filename, "rb").read() != self.contents):
                    direction = conflict_handler.wrong_old_contents(filename,
                                                                    self.contents)
                    if  direction != "continue":
                        return
                os.unlink(filename)
            except IOError, e:
                if e.errno != errno.ENOENT:
                    raise
                if conflict_handler.missing_for_rm(filename, undo) == "skip":
                    return

                    

def reversed(sequence):
    max = len(sequence) - 1
    for i in range(len(sequence)):
        yield sequence[max - i]

class ReplaceContents(object):
    """A contents-replacement framework.  It allows a file/directory/symlink to
    be created, deleted, or replaced with another file/directory/symlink.
    Arguments must be callable with (filename, reverse).
    """
    def __init__(self, old_contents, new_contents):
        """Constructor.

        :param old_contents: The change to reverse apply (e.g. a deletion), \
        when going forwards.
        :type old_contents: `dir_create`, `SymlinkCreate`, `FileCreate`, \
        NoneType, etc.
        :param new_contents: The second change to apply (e.g. a creation), \
        when going forwards.
        :type new_contents: `dir_create`, `SymlinkCreate`, `FileCreate`, \
        NoneType, etc.
        """
        self.old_contents=old_contents
        self.new_contents=new_contents

    def __repr__(self):
        return "ReplaceContents(%r -> %r)" % (self.old_contents,
                                              self.new_contents)

    def __eq__(self, other):
        if not isinstance(other, ReplaceContents):
            return False
        elif self.old_contents != other.old_contents:
            return False
        elif self.new_contents != other.new_contents:
            return False
        else:
            return True
    def __ne__(self, other):
        return not (self == other)

    def apply(self, filename, conflict_handler, reverse=False):
        """Applies the FileReplacement to the specified filename

        :param filename: The name of the file to apply changes to
        :type filename: str
        :param reverse: If true, apply the change in reverse
        :type reverse: bool
        """
        if not reverse:
            undo = self.old_contents
            perform = self.new_contents
        else:
            undo = self.new_contents
            perform = self.old_contents
        mode = None
        if undo is not None:
            try:
                mode = os.lstat(filename).st_mode
                if stat.S_ISLNK(mode):
                    mode = None
            except OSError, e:
                if e.errno != errno.ENOENT:
                    raise
                if conflict_handler.missing_for_rm(filename, undo) == "skip":
                    return
            undo(filename, conflict_handler, reverse=True)
        if perform is not None:
            perform(filename, conflict_handler, reverse=False)
            if mode is not None:
                os.chmod(filename, mode)

class ApplySequence(object):
    def __init__(self, changes=None):
        self.changes = []
        if changes is not None:
            self.changes.extend(changes)

    def __eq__(self, other):
        if not isinstance(other, ApplySequence):
            return False
        elif len(other.changes) != len(self.changes):
            return False
        else:
            for i in range(len(self.changes)):
                if self.changes[i] != other.changes[i]:
                    return False
            return True

    def __ne__(self, other):
        return not (self == other)

    
    def apply(self, filename, conflict_handler, reverse=False):
        if not reverse:
            iter = self.changes
        else:
            iter = reversed(self.changes)
        for change in iter:
            change.apply(filename, conflict_handler, reverse)


class Diff3Merge(object):
    def __init__(self, file_id, base, other):
        self.file_id = file_id
        self.base = base
        self.other = other

    def __eq__(self, other):
        if not isinstance(other, Diff3Merge):
            return False
        return (self.base == other.base and 
                self.other == other.other and self.file_id == other.file_id)

    def __ne__(self, other):
        return not (self == other)

    def apply(self, filename, conflict_handler, reverse=False):
        new_file = filename+".new"
        base_file = self.base.readonly_path(self.file_id)
        other_file = self.other.readonly_path(self.file_id)
        if not reverse:
            base = base_file
            other = other_file
        else:
            base = other_file
            other = base_file
        status = patch.diff3(new_file, filename, base, other)
        if status == 0:
            os.chmod(new_file, os.stat(filename).st_mode)
            rename(new_file, filename)
            return
        else:
            assert(status == 1)
            def get_lines(filename):
                my_file = file(base, "rb")
                lines = my_file.readlines()
                my_file.close()
            base_lines = get_lines(base)
            other_lines = get_lines(other)
            conflict_handler.merge_conflict(new_file, filename, base_lines, 
                                            other_lines)


def CreateDir():
    """Convenience function to create a directory.

    :return: A ReplaceContents that will create a directory
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(None, dir_create)

def DeleteDir():
    """Convenience function to delete a directory.

    :return: A ReplaceContents that will delete a directory
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(dir_create, None)

def CreateFile(contents):
    """Convenience fucntion to create a file.
    
    :param contents: The contents of the file to create 
    :type contents: str
    :return: A ReplaceContents that will create a file 
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(None, FileCreate(contents))

def DeleteFile(contents):
    """Convenience fucntion to delete a file.
    
    :param contents: The contents of the file to delete
    :type contents: str
    :return: A ReplaceContents that will delete a file 
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(FileCreate(contents), None)

def ReplaceFileContents(old_contents, new_contents):
    """Convenience fucntion to replace the contents of a file.
    
    :param old_contents: The contents of the file to replace 
    :type old_contents: str
    :param new_contents: The contents to replace the file with
    :type new_contents: str
    :return: A ReplaceContents that will replace the contents of a file a file 
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(FileCreate(old_contents), FileCreate(new_contents))

def CreateSymlink(target):
    """Convenience fucntion to create a symlink.
    
    :param target: The path the link should point to
    :type target: str
    :return: A ReplaceContents that will delete a file 
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(None, SymlinkCreate(target))

def DeleteSymlink(target):
    """Convenience fucntion to delete a symlink.
    
    :param target: The path the link should point to
    :type target: str
    :return: A ReplaceContents that will delete a file 
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(SymlinkCreate(target), None)

def ChangeTarget(old_target, new_target):
    """Convenience fucntion to change the target of a symlink.
    
    :param old_target: The current link target
    :type old_target: str
    :param new_target: The new link target to use
    :type new_target: str
    :return: A ReplaceContents that will delete a file 
    :rtype: `ReplaceContents`
    """
    return ReplaceContents(SymlinkCreate(old_target), SymlinkCreate(new_target))


class InvalidEntry(Exception):
    """Raise when a ChangesetEntry is invalid in some way"""
    def __init__(self, entry, problem):
        """Constructor.

        :param entry: The invalid ChangesetEntry
        :type entry: `ChangesetEntry`
        :param problem: The problem with the entry
        :type problem: str
        """
        msg = "Changeset entry for %s (%s) is invalid.\n%s" % (entry.id, 
                                                               entry.path, 
                                                               problem)
        Exception.__init__(self, msg)
        self.entry = entry


class SourceRootHasName(InvalidEntry):
    """This changeset entry has a name other than "", but its parent is !NULL"""
    def __init__(self, entry, name):
        """Constructor.

        :param entry: The invalid ChangesetEntry
        :type entry: `ChangesetEntry`
        :param name: The name of the entry
        :type name: str
        """
        msg = 'Child of !NULL is named "%s", not "./.".' % name
        InvalidEntry.__init__(self, entry, msg)

class NullIDAssigned(InvalidEntry):
    """The id !NULL was assigned to a real entry"""
    def __init__(self, entry):
        """Constructor.

        :param entry: The invalid ChangesetEntry
        :type entry: `ChangesetEntry`
        """
        msg = '"!NULL" id assigned to a file "%s".' % entry.path
        InvalidEntry.__init__(self, entry, msg)

class ParentIDIsSelf(InvalidEntry):
    """An entry is marked as its own parent"""
    def __init__(self, entry):
        """Constructor.

        :param entry: The invalid ChangesetEntry
        :type entry: `ChangesetEntry`
        """
        msg = 'file %s has "%s" id for both self id and parent id.' % \
            (entry.path, entry.id)
        InvalidEntry.__init__(self, entry, msg)

class ChangesetEntry(object):
    """An entry the changeset"""
    def __init__(self, id, parent, path):
        """Constructor. Sets parent and name assuming it was not
        renamed/created/deleted.
        :param id: The id associated with the entry
        :param parent: The id of the parent of this entry (or !NULL if no
        parent)
        :param path: The file path relative to the tree root of this entry
        """
        self.id = id
        self.path = path 
        self.new_path = path
        self.parent = parent
        self.new_parent = parent
        self.contents_change = None
        self.metadata_change = None
        if parent == NULL_ID and path !='./.':
            raise SourceRootHasName(self, path)
        if self.id == NULL_ID:
            raise NullIDAssigned(self)
        if self.id  == self.parent:
            raise ParentIDIsSelf(self)

    def __str__(self):
        return "ChangesetEntry(%s)" % self.id

    def __get_dir(self):
        if self.path is None:
            return None
        return os.path.dirname(self.path)

    def __set_dir(self, dir):
        self.path = os.path.join(dir, os.path.basename(self.path))

    dir = property(__get_dir, __set_dir)
    
    def __get_name(self):
        if self.path is None:
            return None
        return os.path.basename(self.path)

    def __set_name(self, name):
        self.path = os.path.join(os.path.dirname(self.path), name)

    name = property(__get_name, __set_name)

    def __get_new_dir(self):
        if self.new_path is None:
            return None
        return os.path.dirname(self.new_path)

    def __set_new_dir(self, dir):
        self.new_path = os.path.join(dir, os.path.basename(self.new_path))

    new_dir = property(__get_new_dir, __set_new_dir)

    def __get_new_name(self):
        if self.new_path is None:
            return None
        return os.path.basename(self.new_path)

    def __set_new_name(self, name):
        self.new_path = os.path.join(os.path.dirname(self.new_path), name)

    new_name = property(__get_new_name, __set_new_name)

    def needs_rename(self):
        """Determines whether the entry requires renaming.

        :rtype: bool
        """

        return (self.parent != self.new_parent or self.name != self.new_name)

    def is_deletion(self, reverse):
        """Return true if applying the entry would delete a file/directory.

        :param reverse: if true, the changeset is being applied in reverse
        :rtype: bool
        """
        return ((self.new_parent is None and not reverse) or 
                (self.parent is None and reverse))

    def is_creation(self, reverse):
        """Return true if applying the entry would create a file/directory.

        :param reverse: if true, the changeset is being applied in reverse
        :rtype: bool
        """
        return ((self.parent is None and not reverse) or 
                (self.new_parent is None and reverse))

    def is_creation_or_deletion(self):
        """Return true if applying the entry would create or delete a 
        file/directory.

        :rtype: bool
        """
        return self.parent is None or self.new_parent is None

    def get_cset_path(self, mod=False):
        """Determine the path of the entry according to the changeset.

        :param changeset: The changeset to derive the path from
        :type changeset: `Changeset`
        :param mod: If true, generate the MOD path.  Otherwise, generate the \
        ORIG path.
        :return: the path of the entry, or None if it did not exist in the \
        requested tree.
        :rtype: str or NoneType
        """
        if mod:
            if self.new_parent == NULL_ID:
                return "./."
            elif self.new_parent is None:
                return None
            return self.new_path
        else:
            if self.parent == NULL_ID:
                return "./."
            elif self.parent is None:
                return None
            return self.path

    def summarize_name(self, reverse=False):
        """Produce a one-line summary of the filename.  Indicates renames as
        old => new, indicates creation as None => new, indicates deletion as
        old => None.

        :param changeset: The changeset to get paths from
        :type changeset: `Changeset`
        :param reverse: If true, reverse the names in the output
        :type reverse: bool
        :rtype: str
        """
        orig_path = self.get_cset_path(False)
        mod_path = self.get_cset_path(True)
        if orig_path is not None:
            orig_path = orig_path[2:]
        if mod_path is not None:
            mod_path = mod_path[2:]
        if orig_path == mod_path:
            return orig_path
        else:
            if not reverse:
                return "%s => %s" % (orig_path, mod_path)
            else:
                return "%s => %s" % (mod_path, orig_path)


    def get_new_path(self, id_map, changeset, reverse=False):
        """Determine the full pathname to rename to

        :param id_map: The map of ids to filenames for the tree
        :type id_map: Dictionary
        :param changeset: The changeset to get data from
        :type changeset: `Changeset`
        :param reverse: If true, we're applying the changeset in reverse
        :type reverse: bool
        :rtype: str
        """
        mutter("Finding new path for %s" % self.summarize_name())
        if reverse:
            parent = self.parent
            to_dir = self.dir
            from_dir = self.new_dir
            to_name = self.name
            from_name = self.new_name
        else:
            parent = self.new_parent
            to_dir = self.new_dir
            from_dir = self.dir
            to_name = self.new_name
            from_name = self.name

        if to_name is None:
            return None

        if parent == NULL_ID or parent is None:
            if to_name != '.':
                raise SourceRootHasName(self, to_name)
            else:
                return '.'
        if from_dir == to_dir:
            dir = os.path.dirname(id_map[self.id])
        else:
            mutter("path, new_path: %r %r" % (self.path, self.new_path))
            parent_entry = changeset.entries[parent]
            dir = parent_entry.get_new_path(id_map, changeset, reverse)
        if from_name == to_name:
            name = os.path.basename(id_map[self.id])
        else:
            name = to_name
            assert(from_name is None or from_name == os.path.basename(id_map[self.id]))
        return os.path.join(dir, name)

    def is_boring(self):
        """Determines whether the entry does nothing
        
        :return: True if the entry does no renames or content changes
        :rtype: bool
        """
        if self.contents_change is not None:
            return False
        elif self.metadata_change is not None:
            return False
        elif self.parent != self.new_parent:
            return False
        elif self.name != self.new_name:
            return False
        else:
            return True

    def apply(self, filename, conflict_handler, reverse=False):
        """Applies the file content and/or metadata changes.

        :param filename: the filename of the entry
        :type filename: str
        :param reverse: If true, apply the changes in reverse
        :type reverse: bool
        """
        if self.is_deletion(reverse) and self.metadata_change is not None:
            self.metadata_change.apply(filename, conflict_handler, reverse)
        if self.contents_change is not None:
            self.contents_change.apply(filename, conflict_handler, reverse)
        if not self.is_deletion(reverse) and self.metadata_change is not None:
            self.metadata_change.apply(filename, conflict_handler, reverse)

class IDPresent(Exception):
    def __init__(self, id):
        msg = "Cannot add entry because that id has already been used:\n%s" %\
            id
        Exception.__init__(self, msg)
        self.id = id

class Changeset(object):
    """A set of changes to apply"""
    def __init__(self):
        self.entries = {}

    def add_entry(self, entry):
        """Add an entry to the list of entries"""
        if self.entries.has_key(entry.id):
            raise IDPresent(entry.id)
        self.entries[entry.id] = entry

def my_sort(sequence, key, reverse=False):
    """A sort function that supports supplying a key for comparison
    
    :param sequence: The sequence to sort
    :param key: A callable object that returns the values to be compared
    :param reverse: If true, sort in reverse order
    :type reverse: bool
    """
    def cmp_by_key(entry_a, entry_b):
        if reverse:
            tmp=entry_a
            entry_a = entry_b
            entry_b = tmp
        return cmp(key(entry_a), key(entry_b))
    sequence.sort(cmp_by_key)

def get_rename_entries(changeset, inventory, reverse):
    """Return a list of entries that will be renamed.  Entries are sorted from
    longest to shortest source path and from shortest to longest target path.

    :param changeset: The changeset to look in
    :type changeset: `Changeset`
    :param inventory: The source of current tree paths for the given ids
    :type inventory: Dictionary
    :param reverse: If true, the changeset is being applied in reverse
    :type reverse: bool
    :return: source entries and target entries as a tuple
    :rtype: (List, List)
    """
    source_entries = [x for x in changeset.entries.itervalues() 
                      if x.needs_rename()]
    # these are done from longest path to shortest, to avoid deleting a
    # parent before its children are deleted/renamed 
    def longest_to_shortest(entry):
        path = inventory.get(entry.id)
        if path is None:
            return 0
        else:
            return len(path)
    my_sort(source_entries, longest_to_shortest, reverse=True)

    target_entries = source_entries[:]
    # These are done from shortest to longest path, to avoid creating a
    # child before its parent has been created/renamed
    def shortest_to_longest(entry):
        path = entry.get_new_path(inventory, changeset, reverse)
        if path is None:
            return 0
        else:
            return len(path)
    my_sort(target_entries, shortest_to_longest)
    return (source_entries, target_entries)

def rename_to_temp_delete(source_entries, inventory, dir, temp_dir, 
                          conflict_handler, reverse):
    """Delete and rename entries as appropriate.  Entries are renamed to temp
    names.  A map of id -> temp name (or None, for deletions) is returned.

    :param source_entries: The entries to rename and delete
    :type source_entries: List of `ChangesetEntry`
    :param inventory: The map of id -> filename in the current tree
    :type inventory: Dictionary
    :param dir: The directory to apply changes to
    :type dir: str
    :param reverse: Apply changes in reverse
    :type reverse: bool
    :return: a mapping of id to temporary name
    :rtype: Dictionary
    """
    temp_name = {}
    for i in range(len(source_entries)):
        entry = source_entries[i]
        if entry.is_deletion(reverse):
            path = os.path.join(dir, inventory[entry.id])
            entry.apply(path, conflict_handler, reverse)
            temp_name[entry.id] = None

        else:
            to_name = os.path.join(temp_dir, str(i))
            src_path = inventory.get(entry.id)
            if src_path is not None:
                src_path = os.path.join(dir, src_path)
                try:
                    rename(src_path, to_name)
                    temp_name[entry.id] = to_name
                except OSError, e:
                    if e.errno != errno.ENOENT:
                        raise
                    if conflict_handler.missing_for_rename(src_path) == "skip":
                        continue

    return temp_name


def rename_to_new_create(changed_inventory, target_entries, inventory, 
                         changeset, dir, conflict_handler, reverse):
    """Rename entries with temp names to their final names, create new files.

    :param changed_inventory: A mapping of id to temporary name
    :type changed_inventory: Dictionary
    :param target_entries: The entries to apply changes to
    :type target_entries: List of `ChangesetEntry`
    :param changeset: The changeset to apply
    :type changeset: `Changeset`
    :param dir: The directory to apply changes to
    :type dir: str
    :param reverse: If true, apply changes in reverse
    :type reverse: bool
    """
    for entry in target_entries:
        new_tree_path = entry.get_new_path(inventory, changeset, reverse)
        if new_tree_path is None:
            continue
        new_path = os.path.join(dir, new_tree_path)
        old_path = changed_inventory.get(entry.id)
        if os.path.exists(new_path):
            if conflict_handler.target_exists(entry, new_path, old_path) == \
                "skip":
                continue
        if entry.is_creation(reverse):
            entry.apply(new_path, conflict_handler, reverse)
            changed_inventory[entry.id] = new_tree_path
        else:
            if old_path is None:
                continue
            try:
                rename(old_path, new_path)
                changed_inventory[entry.id] = new_tree_path
            except OSError, e:
                raise Exception ("%s is missing" % new_path)

class TargetExists(Exception):
    def __init__(self, entry, target):
        msg = "The path %s already exists" % target
        Exception.__init__(self, msg)
        self.entry = entry
        self.target = target

class RenameConflict(Exception):
    def __init__(self, id, this_name, base_name, other_name):
        msg = """Trees all have different names for a file
 this: %s
 base: %s
other: %s
   id: %s""" % (this_name, base_name, other_name, id)
        Exception.__init__(self, msg)
        self.this_name = this_name
        self.base_name = base_name
        self_other_name = other_name

class MoveConflict(Exception):
    def __init__(self, id, this_parent, base_parent, other_parent):
        msg = """The file is in different directories in every tree
 this: %s
 base: %s
other: %s
   id: %s""" % (this_parent, base_parent, other_parent, id)
        Exception.__init__(self, msg)
        self.this_parent = this_parent
        self.base_parent = base_parent
        self_other_parent = other_parent

class MergeConflict(Exception):
    def __init__(self, this_path):
        Exception.__init__(self, "Conflict applying changes to %s" % this_path)
        self.this_path = this_path

class MergePermissionConflict(Exception):
    def __init__(self, this_path, base_path, other_path):
        this_perms = os.stat(this_path).st_mode & 0755
        base_perms = os.stat(base_path).st_mode & 0755
        other_perms = os.stat(other_path).st_mode & 0755
        msg = """Conflicting permission for %s
this: %o
base: %o
other: %o
        """ % (this_path, this_perms, base_perms, other_perms)
        self.this_path = this_path
        self.base_path = base_path
        self.other_path = other_path
        Exception.__init__(self, msg)

class WrongOldContents(Exception):
    def __init__(self, filename):
        msg = "Contents mismatch deleting %s" % filename
        self.filename = filename
        Exception.__init__(self, msg)

class WrongOldPermissions(Exception):
    def __init__(self, filename, old_perms, new_perms):
        msg = "Permission missmatch on %s:\n" \
        "Expected 0%o, got 0%o." % (filename, old_perms, new_perms)
        self.filename = filename
        Exception.__init__(self, msg)

class RemoveContentsConflict(Exception):
    def __init__(self, filename):
        msg = "Conflict deleting %s, which has different contents in BASE"\
            " and THIS" % filename
        self.filename = filename
        Exception.__init__(self, msg)

class DeletingNonEmptyDirectory(Exception):
    def __init__(self, filename):
        msg = "Trying to remove dir %s while it still had files" % filename
        self.filename = filename
        Exception.__init__(self, msg)


class PatchTargetMissing(Exception):
    def __init__(self, filename):
        msg = "Attempt to patch %s, which does not exist" % filename
        Exception.__init__(self, msg)
        self.filename = filename

class MissingPermsFile(Exception):
    def __init__(self, filename):
        msg = "Attempt to change permissions on  %s, which does not exist" %\
            filename
        Exception.__init__(self, msg)
        self.filename = filename

class MissingForRm(Exception):
    def __init__(self, filename):
        msg = "Attempt to remove missing path %s" % filename
        Exception.__init__(self, msg)
        self.filename = filename


class MissingForRename(Exception):
    def __init__(self, filename):
        msg = "Attempt to move missing path %s" % (filename)
        Exception.__init__(self, msg)
        self.filename = filename

class NewContentsConflict(Exception):
    def __init__(self, filename):
        msg = "Conflicting contents for new file %s" % (filename)
        Exception.__init__(self, msg)


class MissingForMerge(Exception):
    def __init__(self, filename):
        msg = "The file %s was modified, but does not exist in this tree"\
            % (filename)
        Exception.__init__(self, msg)


class ExceptionConflictHandler(object):
    """Default handler for merge exceptions.

    This throws an error on any kind of conflict.  Conflict handlers can
    descend from this class if they have a better way to handle some or
    all types of conflict.
    """
    def missing_parent(self, pathname):
        parent = os.path.dirname(pathname)
        raise Exception("Parent directory missing for %s" % pathname)

    def dir_exists(self, pathname):
        raise Exception("Directory already exists for %s" % pathname)

    def failed_hunks(self, pathname):
        raise Exception("Failed to apply some hunks for %s" % pathname)

    def target_exists(self, entry, target, old_path):
        raise TargetExists(entry, target)

    def rename_conflict(self, id, this_name, base_name, other_name):
        raise RenameConflict(id, this_name, base_name, other_name)

    def move_conflict(self, id, this_dir, base_dir, other_dir):
        raise MoveConflict(id, this_dir, base_dir, other_dir)

    def merge_conflict(self, new_file, this_path, base_lines, other_lines):
        os.unlink(new_file)
        raise MergeConflict(this_path)

    def permission_conflict(self, this_path, base_path, other_path):
        raise MergePermissionConflict(this_path, base_path, other_path)

    def wrong_old_contents(self, filename, expected_contents):
        raise WrongOldContents(filename)

    def rem_contents_conflict(self, filename, this_contents, base_contents):
        raise RemoveContentsConflict(filename)

    def wrong_old_perms(self, filename, old_perms, new_perms):
        raise WrongOldPermissions(filename, old_perms, new_perms)

    def rmdir_non_empty(self, filename):
        raise DeletingNonEmptyDirectory(filename)

    def link_name_exists(self, filename):
        raise TargetExists(filename)

    def patch_target_missing(self, filename, contents):
        raise PatchTargetMissing(filename)

    def missing_for_chmod(self, filename):
        raise MissingPermsFile(filename)

    def missing_for_rm(self, filename, change):
        raise MissingForRm(filename)

    def missing_for_rename(self, filename):
        raise MissingForRename(filename)

    def missing_for_merge(self, file_id, other_path):
        raise MissingForMerge(other_path)

    def new_contents_conflict(self, filename, other_contents):
        raise NewContentsConflict(filename)

    def finalize(self):
        pass

def apply_changeset(changeset, inventory, dir, conflict_handler=None, 
                    reverse=False):
    """Apply a changeset to a directory.

    :param changeset: The changes to perform
    :type changeset: `Changeset`
    :param inventory: The mapping of id to filename for the directory
    :type inventory: Dictionary
    :param dir: The path of the directory to apply the changes to
    :type dir: str
    :param reverse: If true, apply the changes in reverse
    :type reverse: bool
    :return: The mapping of the changed entries
    :rtype: Dictionary
    """
    if conflict_handler is None:
        conflict_handler = ExceptionConflictHandler()
    temp_dir = os.path.join(dir, "bzr-tree-change")
    try:
        os.mkdir(temp_dir)
    except OSError, e:
        if e.errno == errno.EEXIST:
            try:
                os.rmdir(temp_dir)
            except OSError, e:
                if e.errno == errno.ENOTEMPTY:
                    raise OldFailedTreeOp()
            os.mkdir(temp_dir)
        else:
            raise
    
    #apply changes that don't affect filenames
    for entry in changeset.entries.itervalues():
        if not entry.is_creation_or_deletion():
            path = os.path.join(dir, inventory[entry.id])
            entry.apply(path, conflict_handler, reverse)

    # Apply renames in stages, to minimize conflicts:
    # Only files whose name or parent change are interesting, because their
    # target name may exist in the source tree.  If a directory's name changes,
    # that doesn't make its children interesting.
    (source_entries, target_entries) = get_rename_entries(changeset, inventory,
                                                          reverse)

    changed_inventory = rename_to_temp_delete(source_entries, inventory, dir,
                                              temp_dir, conflict_handler,
                                              reverse)

    rename_to_new_create(changed_inventory, target_entries, inventory,
                         changeset, dir, conflict_handler, reverse)
    os.rmdir(temp_dir)
    return changed_inventory


def apply_changeset_tree(cset, tree, reverse=False):
    r_inventory = {}
    for entry in tree.source_inventory().itervalues():
        inventory[entry.id] = entry.path
    new_inventory = apply_changeset(cset, r_inventory, tree.root,
                                    reverse=reverse)
    new_entries, remove_entries = \
        get_inventory_change(inventory, new_inventory, cset, reverse)
    tree.update_source_inventory(new_entries, remove_entries)


def get_inventory_change(inventory, new_inventory, cset, reverse=False):
    new_entries = {}
    remove_entries = []
    for entry in cset.entries.itervalues():
        if entry.needs_rename():
            new_path = entry.get_new_path(inventory, cset)
            if new_path is None:
                remove_entries.append(entry.id)
            else:
                new_entries[new_path] = entry.id
    return new_entries, remove_entries


def print_changeset(cset):
    """Print all non-boring changeset entries
    
    :param cset: The changeset to print
    :type cset: `Changeset`
    """
    for entry in cset.entries.itervalues():
        if entry.is_boring():
            continue
        print entry.id
        print entry.summarize_name(cset)

class CompositionFailure(Exception):
    def __init__(self, old_entry, new_entry, problem):
        msg = "Unable to conpose entries.\n %s" % problem
        Exception.__init__(self, msg)

class IDMismatch(CompositionFailure):
    def __init__(self, old_entry, new_entry):
        problem = "Attempt to compose entries with different ids: %s and %s" %\
            (old_entry.id, new_entry.id)
        CompositionFailure.__init__(self, old_entry, new_entry, problem)

def compose_changesets(old_cset, new_cset):
    """Combine two changesets into one.  This works well for exact patching.
    Otherwise, not so well.

    :param old_cset: The first changeset that would be applied
    :type old_cset: `Changeset`
    :param new_cset: The second changeset that would be applied
    :type new_cset: `Changeset`
    :return: A changeset that combines the changes in both changesets
    :rtype: `Changeset`
    """
    composed = Changeset()
    for old_entry in old_cset.entries.itervalues():
        new_entry = new_cset.entries.get(old_entry.id)
        if new_entry is None:
            composed.add_entry(old_entry)
        else:
            composed_entry = compose_entries(old_entry, new_entry)
            if composed_entry.parent is not None or\
                composed_entry.new_parent is not None:
                composed.add_entry(composed_entry)
    for new_entry in new_cset.entries.itervalues():
        if not old_cset.entries.has_key(new_entry.id):
            composed.add_entry(new_entry)
    return composed

def compose_entries(old_entry, new_entry):
    """Combine two entries into one.

    :param old_entry: The first entry that would be applied
    :type old_entry: ChangesetEntry
    :param old_entry: The second entry that would be applied
    :type old_entry: ChangesetEntry
    :return: A changeset entry combining both entries
    :rtype: `ChangesetEntry`
    """
    if old_entry.id != new_entry.id:
        raise IDMismatch(old_entry, new_entry)
    output = ChangesetEntry(old_entry.id, old_entry.parent, old_entry.path)

    if (old_entry.parent != old_entry.new_parent or 
        new_entry.parent != new_entry.new_parent):
        output.new_parent = new_entry.new_parent

    if (old_entry.path != old_entry.new_path or 
        new_entry.path != new_entry.new_path):
        output.new_path = new_entry.new_path

    output.contents_change = compose_contents(old_entry, new_entry)
    output.metadata_change = compose_metadata(old_entry, new_entry)
    return output

def compose_contents(old_entry, new_entry):
    """Combine the contents of two changeset entries.  Entries are combined
    intelligently where possible, but the fallback behavior returns an 
    ApplySequence.

    :param old_entry: The first entry that would be applied
    :type old_entry: `ChangesetEntry`
    :param new_entry: The second entry that would be applied
    :type new_entry: `ChangesetEntry`
    :return: A combined contents change
    :rtype: anything supporting the apply(reverse=False) method
    """
    old_contents = old_entry.contents_change
    new_contents = new_entry.contents_change
    if old_entry.contents_change is None:
        return new_entry.contents_change
    elif new_entry.contents_change is None:
        return old_entry.contents_change
    elif isinstance(old_contents, ReplaceContents) and \
        isinstance(new_contents, ReplaceContents):
        if old_contents.old_contents == new_contents.new_contents:
            return None
        else:
            return ReplaceContents(old_contents.old_contents,
                                   new_contents.new_contents)
    elif isinstance(old_contents, ApplySequence):
        output = ApplySequence(old_contents.changes)
        if isinstance(new_contents, ApplySequence):
            output.changes.extend(new_contents.changes)
        else:
            output.changes.append(new_contents)
        return output
    elif isinstance(new_contents, ApplySequence):
        output = ApplySequence((old_contents.changes,))
        output.extend(new_contents.changes)
        return output
    else:
        return ApplySequence((old_contents, new_contents))

def compose_metadata(old_entry, new_entry):
    old_meta = old_entry.metadata_change
    new_meta = new_entry.metadata_change
    if old_meta is None:
        return new_meta
    elif new_meta is None:
        return old_meta
    elif isinstance(old_meta, ChangeUnixPermissions) and \
        isinstance(new_meta, ChangeUnixPermissions):
        return ChangeUnixPermissions(old_meta.old_mode, new_meta.new_mode)
    else:
        return ApplySequence(old_meta, new_meta)


def changeset_is_null(changeset):
    for entry in changeset.entries.itervalues():
        if not entry.is_boring():
            return False
    return True

class UnsuppportedFiletype(Exception):
    def __init__(self, full_path, stat_result):
        msg = "The file \"%s\" is not a supported filetype." % full_path
        Exception.__init__(self, msg)
        self.full_path = full_path
        self.stat_result = stat_result

def generate_changeset(tree_a, tree_b, interesting_ids=None):
    return ChangesetGenerator(tree_a, tree_b, interesting_ids)()

class ChangesetGenerator(object):
    def __init__(self, tree_a, tree_b, interesting_ids=None):
        object.__init__(self)
        self.tree_a = tree_a
        self.tree_b = tree_b
        self._interesting_ids = interesting_ids

    def iter_both_tree_ids(self):
        for file_id in self.tree_a:
            yield file_id
        for file_id in self.tree_b:
            if file_id not in self.tree_a:
                yield file_id

    def __call__(self):
        cset = Changeset()
        for file_id in self.iter_both_tree_ids():
            cs_entry = self.make_entry(file_id)
            if cs_entry is not None and not cs_entry.is_boring():
                cset.add_entry(cs_entry)

        for entry in list(cset.entries.itervalues()):
            if entry.parent != entry.new_parent:
                if not cset.entries.has_key(entry.parent) and\
                    entry.parent != NULL_ID and entry.parent is not None:
                    parent_entry = self.make_boring_entry(entry.parent)
                    cset.add_entry(parent_entry)
                if not cset.entries.has_key(entry.new_parent) and\
                    entry.new_parent != NULL_ID and \
                    entry.new_parent is not None:
                    parent_entry = self.make_boring_entry(entry.new_parent)
                    cset.add_entry(parent_entry)
        return cset

    def iter_inventory(self, tree):
        for file_id in tree:
            yield self.get_entry(file_id, tree)

    def get_entry(self, file_id, tree):
        if not tree.has_or_had_id(file_id):
            return None
        return tree.tree.inventory[file_id]

    def get_entry_parent(self, entry):
        if entry is None:
            return None
        return entry.parent_id

    def get_path(self, file_id, tree):
        if not tree.has_or_had_id(file_id):
            return None
        path = tree.id2path(file_id)
        if path == '':
            return './.'
        else:
            return path

    def make_basic_entry(self, file_id, only_interesting):
        entry_a = self.get_entry(file_id, self.tree_a)
        entry_b = self.get_entry(file_id, self.tree_b)
        if only_interesting and not self.is_interesting(entry_a, entry_b):
            return None
        parent = self.get_entry_parent(entry_a)
        path = self.get_path(file_id, self.tree_a)
        cs_entry = ChangesetEntry(file_id, parent, path)
        new_parent = self.get_entry_parent(entry_b)

        new_path = self.get_path(file_id, self.tree_b)

        cs_entry.new_path = new_path
        cs_entry.new_parent = new_parent
        return cs_entry

    def is_interesting(self, entry_a, entry_b):
        if self._interesting_ids is None:
            return True
        if entry_a is not None:
            file_id = entry_a.file_id
        elif entry_b is not None:
            file_id = entry_b.file_id
        else:
            return False
        return file_id in self._interesting_ids

    def make_boring_entry(self, id):
        cs_entry = self.make_basic_entry(id, only_interesting=False)
        if cs_entry.is_creation_or_deletion():
            return self.make_entry(id, only_interesting=False)
        else:
            return cs_entry
        

    def make_entry(self, id, only_interesting=True):
        cs_entry = self.make_basic_entry(id, only_interesting)

        if cs_entry is None:
            return None
        if id in self.tree_a and id in self.tree_b:
            a_sha1 = self.tree_a.get_file_sha1(id)
            b_sha1 = self.tree_b.get_file_sha1(id)
            if None not in (a_sha1, b_sha1) and a_sha1 == b_sha1:
                return cs_entry

        full_path_a = self.tree_a.readonly_path(id)
        full_path_b = self.tree_b.readonly_path(id)
        stat_a = self.lstat(full_path_a)
        stat_b = self.lstat(full_path_b)
        
        cs_entry.metadata_change = self.make_mode_change(stat_a, stat_b)
        cs_entry.contents_change = self.make_contents_change(full_path_a,
                                                             stat_a, 
                                                             full_path_b, 
                                                             stat_b)
        return cs_entry

    def make_mode_change(self, stat_a, stat_b):
        mode_a = None
        if stat_a is not None and not stat.S_ISLNK(stat_a.st_mode):
            mode_a = stat_a.st_mode & 0777
        mode_b = None
        if stat_b is not None and not stat.S_ISLNK(stat_b.st_mode):
            mode_b = stat_b.st_mode & 0777
        if mode_a == mode_b:
            return None
        return ChangeUnixPermissions(mode_a, mode_b)

    def make_contents_change(self, full_path_a, stat_a, full_path_b, stat_b):
        if stat_a is None and stat_b is None:
            return None
        if None not in (stat_a, stat_b) and stat.S_ISDIR(stat_a.st_mode) and\
            stat.S_ISDIR(stat_b.st_mode):
            return None
        if None not in (stat_a, stat_b) and stat.S_ISREG(stat_a.st_mode) and\
            stat.S_ISREG(stat_b.st_mode):
            if stat_a.st_ino == stat_b.st_ino and \
                stat_a.st_dev == stat_b.st_dev:
                return None

        a_contents = self.get_contents(stat_a, full_path_a)
        b_contents = self.get_contents(stat_b, full_path_b)
        if a_contents == b_contents:
            return None
        return ReplaceContents(a_contents, b_contents)

    def get_contents(self, stat_result, full_path):
        if stat_result is None:
            return None
        elif stat.S_ISREG(stat_result.st_mode):
            return FileCreate(file(full_path, "rb").read())
        elif stat.S_ISDIR(stat_result.st_mode):
            return dir_create
        elif stat.S_ISLNK(stat_result.st_mode):
            return SymlinkCreate(os.readlink(full_path))
        else:
            raise UnsupportedFiletype(full_path, stat_result)

    def lstat(self, full_path):
        stat_result = None
        if full_path is not None:
            try:
                stat_result = os.lstat(full_path)
            except OSError, e:
                if e.errno != errno.ENOENT:
                    raise
        return stat_result


def full_path(entry, tree):
    return os.path.join(tree.root, entry.path)

def new_delete_entry(entry, tree, inventory, delete):
    if entry.path == "":
        parent = NULL_ID
    else:
        parent = inventory[dirname(entry.path)].id
    cs_entry = ChangesetEntry(parent, entry.path)
    if delete:
        cs_entry.new_path = None
        cs_entry.new_parent = None
    else:
        cs_entry.path = None
        cs_entry.parent = None
    full_path = full_path(entry, tree)
    status = os.lstat(full_path)
    if stat.S_ISDIR(file_stat.st_mode):
        action = dir_create
    


        
# XXX: Can't we unify this with the regular inventory object
class Inventory(object):
    def __init__(self, inventory):
        self.inventory = inventory
        self.rinventory = None

    def get_rinventory(self):
        if self.rinventory is None:
            self.rinventory  = invert_dict(self.inventory)
        return self.rinventory

    def get_path(self, id):
        return self.inventory.get(id)

    def get_name(self, id):
        path = self.get_path(id)
        if path is None:
            return None
        else:
            return os.path.basename(path)

    def get_dir(self, id):
        path = self.get_path(id)
        if path == "":
            return None
        if path is None:
            return None
        return os.path.dirname(path)

    def get_parent(self, id):
        if self.get_path(id) is None:
            return None
        directory = self.get_dir(id)
        if directory == '.':
            directory = './.'
        if directory is None:
            return NULL_ID
        return self.get_rinventory().get(directory)